seraphis-poc.md

layout: cp
title: "koe: Seraphis Proof-of-Concept"
author: koe
date: 1 October 2021
amount: 92.6
milestones:
  - name: PoC
    funds: 100% (92.6 XMR)
    done: 22 February 2022
    status: finished
payouts:
  - date: 25 April 2022
    amount: 92.6

Intro

Hi all, after some encouragement I decided to request funding for my ongoing work on Seraphis. Specifically, funding for future work on the Seraphis C++ proof-of-concept that I have been developing since the second week of September.

My goal is for this code to be 95% production-ready. It is appropriate to get large pieces of code funded if they have a strong potential to be merged into the master branch.

What is Seraphis?

Seraphis is a next-gen transaction protocol abstraction, which means it defines various high-level rules for a concrete transaction protocol. RingCT can be thought of as the current tx protocol abstraction, even though the RingCT paper specified concrete proving structures directly without abstraction.

The main innovation of Seraphis (and Lelantus-Spark, a very similar protocol developed independently) is using only simple commitments-to-zero for showing that a transaction input (an output being spent) exists in the ledger. This allows proofs about key images to be independent of membership proofs, which means one-time addresses and key images can be creatively designed. In particular, it is possible to avoid one of the main drawbacks of Triptych, namely a key image construction that makes multisig much more complicated.

Seraphis has other potential benefits over RingCT and Triptych (depending on concrete design choices):

• membership proof delegation (allows transaction chaining, offloading proof construction to third parties, improved indistinguishability of multisig tx [construct membership proofs at the last minute to avoid leaking timing details], allows the 10-block lock time to be somewhat ignored when transacting with a trusted party)
• multi-tier wallet permissions (e.g. a view-only wallet that can detect spent outputs, a view-only wallet that can see received outputs but not their amounts)

The main costs of Seraphis compared to Triptych are: